In conventional practice, piezoelectric actuators for driving driven objects by the vibration of a vibrator having a piezoelectric element have been used in the calendar mechanisms of timepieces, the zoom mechanisms or auto-focus mechanisms of cameras, the drive mechanisms of mobile toys, and the like.
With timepieces, cameras, mobile toys, or other electronic devices provided with such piezoelectric actuators, the operation may be affected by the fact that the vibrator of the piezoelectric actuator and the rotor or other objects driven by the piezoelectric actuator may be brought out of alignment by external impact that occurs when the device is dropped, and damages may occur if the impact is severe. Particularly, the component that supports and secures the vibrator is generally thin and fragile so as not do disrupt the vibration of the vibrator Therefore, problems are encountered in that the deformation of the vibrator due to impact causes this supporting part to break or causes the wiring provided to the supporting part to be cut.
Methods in which the vibrator is merely supported in a direct manner in order to provide an impact-resistant structure for the piezoelectric actuator are subject to problems in that the support interferes with vibration and reduces drive efficiency.
Therefore, in one proposed impact-resistant structure in which the vibrator is not directly supported, the rotor and the vibrator are prevented from separating during impact. This is achieved by providing a spring member that pushes the rotor towards the vibrator, and providing a pin to a position adjacent to the spring member to regulate the movement of the spring member (Patent Reference 1).
The pin in Patent Reference 1 is provided so as to come into contact with the spring member in cases in which the rotor moves a specific distance in the direction away from the vibrator during impact, and also so as to maintain the state of contact between the piezoelectric actuator and the rotor. The pin is also disposed at a position whereby the rotor will not collide with any other members in cases in which the rotor separates from the vibrator during impact, and whereby the meshing between the rotor and the teeth of the next transmission wheel will not disengage.
[Patent Reference 1] Japanese Laid-open Patent Application No. 2004-301627 (Specification, paragraph no. [0013], FIG. 2)